The present application relates to electronic devices, and in particular, to electronic stickers that can adhere to human skin or the surface of an object.
Wearable patches or tags can communicate with smart phones and other devices using WiFi, Bluetooth, or NFC technologies. Near Field Communication (NFC) is a wireless communication standard which enables two devices in a short range to establish a communication channel within a short period of time through radio waves in the 13.56 MHz frequency range. NFC can be a useful technology for data transfer between two devices in close proximity to one another. Because it needs the two devices to be in close proximity to one another (less than 10 cm), it is more secure than other wireless technologies like Bluetooth and Wi-Fi. Hence, it can be seen as an easy and secure tool for establishing quick two-way connections for data transfer. One of the two NFC devices can be a passive NFC tag that uses passive energy collected through active electromagnetic coupling from the reader devices, so it brings another benefit of no battery in its system that simplify the product design and make disposable product possible.
This communication standard is being increasingly adopted for use in wireless transactions, including money transfer, loyalty coupons, gift cards, transit passes, tickets, etc. Mobile handset manufacturing companies are increasingly integrating NFC hardware in their phones. For example, the 2014 CES badges employed NFC technology and have resulted in shorter lines, more badge functionality, and greater ease of use for attendees and exhibitors. NFC has also been increasingly used in the fields of medical devices, electronic health records, as well as wearable tagging devices.
In other scenarios, long communication distance is required, such as >10 meters. Without tapping the reader device in the close range NFC patch from time to time, data can be collected automatically and continuously with least operator interference. In such cases, Bluetooth and WiFi are a proper option with a 1.5V or 3V battery supply.
Wearable tag or patch is an electronic tag that can be worn by a user. Wearable patch is required to directly stay on user's skin and function for an extended period of time from hours to months. A wearable patch can contain a micro-electronic system and can be accessed using NFC, Bluethooth, WiFi, or other wireless technologies. For example, an authentication wearable tag can be used to recognize a user's smart phone for authentication purpose. It can also be integrated with different sensors for other purposes such as vital signs monitoring, heartbeat, motion track, blood pressure, temperature measurements and ECG detection.
Despite initial development efforts, conventional wearable devices still face several drawbacks: they may not provide adequate comfort for users to wear them; they may not stay attached to user's body for the required length of time; they are usually not aesthetically appealing. Another drawback of conventional wearable patches is that the rigid polymer substrate does not allow much breathability to the skin. The build-up of sweat and moisture can cause discomfort and irritation to the skin, especially after wearing it for an extended period of time. In addition, their rigid substrates are very difficult to conform to curved surfaces, so some critical bio information needs to be collected with direct contact on skin without any air gap. For example, electrocardiography (usually called as ECG) picks up electrical impulses generated by the polarization and depolarization of cardiac tissue and translates into a waveform. The signals need to be detected by electrodes attached directly to the surface of the skin and recorded or displayed by a device external to the body. Air gap between the electrode and skin surface makes the measurement inaccurate. Moreover, conventional wearable devices are often not robust enough to sustain repeated elongations during the movements of the body to which the wearable patches are attached. Under stress, different layers in wearable patches can break or delaminate rendering the patches inoperable.
Wearable tags are a specific type of electronic stickers. In more general cases, electronic stickers can be attached not only to human bodies but also to other objects such as merchandized goods such as computers, smart phones, and clothes, packaging material and shipping boxes. Electronic stickers can communicate with smart phones or other devices wirelessly, through NFC, Bluetooth, WiFi, or other methods.
Electronic stickers can be used for tracking objects, for performing functions such as producing sound, light or vibrations, and so on. As the applications and human needs become more sophisticated and complex, there are a rapidly increasing number of tasks that electronic stickers are required to perform.
There is therefore a need for electronic stickers that can conveniently and economically measure different signals or perform different actuating functions.